--- title: Injector_wiring description: published: true date: 2020-01-06T05:07:36.786Z tags: --- Introduction ------------ Speeduino contains 4 injector control circuits and is capable of supporting up to 8 injectors (and cylinders) with these. Supported Injectors ------------------- Speeduino supports High-Z (aka 'high-impedance' or 'saturated') injectors natively. Low-Z injectors are supported with the addition of resistors wired in series with the signal wires. High-Z injectors are typically those with a resistance greater than 8 Ohms. If "Low-Z" ("peak and hold" or PWM-controlled) injectors that are lower impedance are used, the wiring will require series resistors on each injector to avoid damaging the board with excessive current. The resistor ohms and watt rating can be calculated by Ohm's Law, or use an Internet calculator page such as the [Speeduino Injector Resistor Calculator](http://efistuff.orgfree.com/InjectorResistorCalculator.html). Layout ------ There are a number of ways that the injectors can be wired depending on your configuration and preference. ### 1, 2 and 3 injectors For these configurations, each injector is wired into it's own output from the Speeduino board. ### Up to 4 injectors For 4 cylinders/injectors, there are 2 ways that these can be connected to Speeduino: #### Method 1 The standard method is the same as that used for 6 or 8 cylinder setups, where 2 injectors are connected to each injector channel. In this configuration, only 2 injector channels will be used. The injectors paired together must have their Top Dead Centres (TDC) 360 crank degrees apart.